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Subaru power steering pump

Less whine WRX please

It’s always the way isn’t it? If it isn’t one thing it’s another – case in point for project WRX was just finishing up the pulley swapover when the Subaru power steering pump started to groan like a small business getting a massive tax bill. A power steering noise? And here I was thinking that was the end of the whining in the Rex’s engine bay…

Upon further information as to why the Subaru power steering pump was carrying on as much as it was, I discovered a nasty pool of Dex 3 that had made it’s way onto the block…and it looked liked it had been there for quite some time. After running the pump for a couple of minutes I took the cap off and found more bubbles than a three year olds birthday party – this is definitely something you don’t want to see in your Subaru power steering pump reservoir as bubbles signify air is getting in the system and as a consequence can cause rough steering, juddering and my new Subaru power steering pump racket.

(Depending on the car, air can enter from anywhere along the power steering system including a hole in the pipe or worn rings or seals – the seals on Toyota Soarer/Lexus SC power steering go bad after a while and light steering can often turn into heavy steering wrestling matches at low speeds until fixed again.)

So after plenty of Googling, I discovered that my WRX seems to have one of the earliest Subaru power steering pump setups as I kept running into people who were talking about checking the clamps and o rings on a pipe mine seemed to lack. Luckily most WRX owners have found the solution to a leaky pump is pretty easy and even better, very cheap.  The leak and air getting into the system seems to commonly occur between the power steering pump fluid reservoir and the pump itself – there’s two o rings that sandwich the gap between the two and over time they become too compressed or old and brittle.



To get them out/swap them over it’s pretty simple (and as a bonus you don’t have to take the belt out :

  1. Open up the reservoir and drain out as much power steering fluid as possibly. If it’s any color other than the traditional Dex 3 red (or Subaru Power Steering Pump official fluid redTM) then turf it and get some fresh stuff for later. A hand pump is very helpful or just grab a child’s medicine plastic syringe you were going to throw out and make use of that. Make sure you take out the small filter first to allow access deep in the reservoir – I didn’t realize about the filter and when I lifted the reservoir up, I coated a lot of things in a lovely fountain of Dex 3…

  2. Disconnect the pipe that connects to the reservoir. Make sure you hold it upwards to prevent even more of a mess made then you first anticipated. Tuck it aside (still pointing upwards) to fit in later. It won’t hurt to stuff a couple of rags under it either to combat accidental spillage.

  3. Undo the bolts of the reservoir and lift up, careful to watch any remnants of power steering fluid dripping out. An old rag or t-shirt under the reservoir will be a big help. The first o-ring you’ll need to replace is on the bottom of the reservoir.

  4. There’s usually a plate that sandwiches the second o-ring to the top of the pump, remove the plate to see the now probably tired, slightly shrunken and leaking second o-ring. Replace with a new one. If it doesn’t fit completely and keeps slipping up (like the one I used), the plate will push it into place when you realign it carefully.

subaru power steering noise pump o ring
The second Subaru power steering pump o ring. This one was a mm or two smaller than the provision for it.
  1. While everything’s off you can really get your clean on. A whole new car of degreaser came in very handy for all the grime and spare Dex 3 all over the place as you can see.

  2. Once you’ve got both of the new o rings on, carefully realign the plate and then ease the reservoir back into the Subaru power steering pump hole. Put the bolts back in, tighten up and connect the hose, remembering to clamp it tightly over the end to prevent more bubbles. Put the filter back in the reservoir if it’s still out and slowly fill with the good fluid you saved earlier or some fresh stuff. Pop the cap on and turn it over – with a bit of luck the noise should be gone and the leak between the Subaru power steering pump and it’s reservoir nonexistent.



A box of o-rings – I bought a big box of various sizes and easily found two that fit snugly and create a nice strong seal. (For fellow aussies you’ll find plenty of boxes of them via Supercheap Auto)

Power steering fluid – check the cap to see what proper fluid you should be using. Mine took Dex III but you may need Dex IV instead.

Magnetic pick up stick – Not really necessary for a o ring change usually but if you accidentally drop a bolt into the fans, this took was invaluable to fish it out with..

SUBARU STI OR WRX 03-07 POWER STEERING PUMP Er…hopefully you won’t need one of these as the cheap fixes it. But putting it up here just in case..


If this fixed your power steering noise on your Subaru (or any other model) let us know below! (We love tales of garage success especially when it’s a cheap and easy fix!)


        • Almigo says:

          What year? Mine was from 1994 and as mentioned I had one of the early series pumps. They’re not all going to look the same but if you have a whining noise, changing over easy accesable stuff like O rings are definately worth a try.

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